/**
 * Copyright (C) 2009 eXo Platform SAS.
 *
 * This is free software; you can redistribute it and/or modify it
 * under the terms of the GNU Lesser General Public License as
 * published by the Free Software Foundation; either version 2.1 of
 * the License, or (at your option) any later version.
 *
 * This software is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this software; if not, write to the Free
 * Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
 * 02110-1301 USA, or see the FSF site: http://www.fsf.org.
 */

package org.exoplatform.commons.utils;

import org.gatein.common.io.IOTools;

import java.io.Closeable;
import java.io.IOException;
import java.io.InputStream;
import java.lang.reflect.Field;
import java.lang.reflect.UndeclaredThrowableException;
import java.util.Collections;
import java.util.Set;

/**
 * A class that contains utility method that make the caller not worry much about the unexpectable expected such as
 * argument nullity or the control flow due to exceptions.
 *
 * @author <a href="mailto:julien.viet@exoplatform.com">Julien Viet</a>
 * @version $Revision$
 */
public class Safe
{

   private Safe()
   {
   }

   /**
    * Return true if both objects are null or both are non null and the equals method of one object returns true when it
    * is invoked with the other object as argument.
    *
    * @param o1 the first object
    * @param o2 the second object
    * @return true if string are safely equal
    */
   public static boolean equals(Object o1, Object o2)
   {
      if (o1 == null)
      {
         return o2 == null;
      }
      else
      {
         return o2 != null && o1.equals(o2);
      }
   }

   /**
    * Close a closable object. The provided object may be null or thrown an IOException or a runtime exception during
    * the invocation of the close method without changing the control flow of the method caller. If the closeable was
    * succesfully closed the method returns true.
    *
    * @param closeable the closeable
    * @return true if the object was closed
    */
   public static boolean close(Closeable closeable)
   {
      if (closeable != null)
      {
         try
         {
            closeable.close();
            return true;
         }
         catch (IOException ignore)
         {
         }
         catch (RuntimeException ignore)
         {
         }
      }
      return false;
   }

   public static byte[] getBytes(InputStream is)
   {
      byte[] bytes;

      if (is == null)
      {
         return null;
      }

      try
      {
         bytes = IOTools.getBytes(is);
         return bytes;
      }
      catch (IOException ignore)
      {
         // todo: should log
         return null;
      }
      finally
      {
         IOTools.safeClose(is);
      }
   }

   /**
    * Wrap the set so that it is unmodifiable when it is not null, otherwise returns null.
    *
    * @todo it would be nice to avoid to rewrap unmodifiable set (not sure it is non proprietary possible)
    * @param set the set to wrap
    * @param <E> the set generic element type
    * @return the unmodifiable set
    */
   public static <E> Set<E> unmodifiableSet(Set<E> set)
   {
      if (set == null)
      {
         return null;
      }
      else
      {
         return Collections.unmodifiableSet(set);
      }
   }

   // THIS CODE IS TEMPORARY

   /** . */
   private static final Field listAccessField;

   static
   {
      try
      {
         listAccessField = LazyList.class.getDeclaredField("listAccess");
         listAccessField.setAccessible(true);
      }
      catch (NoSuchFieldException e)
      {
         throw new Error(e);
      }
   }

   public static <E> ListAccess<E> unwrap(PageList<E> pageList)
   {
      LazyPageList<E> lazyPageList = (LazyPageList<E>)pageList;

      //
      try
      {
         // Get LazyList first
         LazyList<E> lazyList = (LazyList<E>)lazyPageList.getAll();

         // Now get list access
         return (ListAccess<E>)listAccessField.get(lazyList);
      }
      catch (Exception e)
      {
         throw new UndeclaredThrowableException(e);
      }
   }
}
